Smart thermostats
Updated
C-wires, wire colors, heat pumps, baseboard heat, mini-splits and room sensors: make sure a smart thermostat fits your system before you buy.
Smart thermostats save the most energy of any smart device, but only if they match your HVAC system. Most central systems in the US use 24-volt control wiring; electric baseboard heat uses line voltage, and gas wall heaters often use millivolt controls, each needing a different type of thermostat.
Turn off power at the breaker or furnace switch before removing an old thermostat, and photograph the wiring. Start with what to do without a C-wire.
Calculators 1
Kits 2
KitEnergy-saving smart home kitA certified smart thermostat, three energy-monitoring plugs, a standby-cutting power strip and optional LED smart bulbs: the shopping list that…KitSmart thermostat installation kit: tools, parts and the thermostatA compatible thermostat, a non-contact voltage tester, a screwdriver set and wire labels are the basics. Optional parts cover a missing C-wire, a…
Guides 12
GuideSmart thermostat without a C-wire: your real optionsNo C-wire at the wall plate? Most homes can still run a smart thermostat. Check your wiring in ten minutes, pick the fix that fits your system and…GuideWhat temperature to set your thermostat to save moneyThe Department of Energy points to 68–70°F when you are awake in winter, a setback of 7–10°F for 8 hours a day and 78°F in summer. Here is how to…GuideSmart thermostat rebates and free thermostat offers from utilitiesMany utilities discount or even give away smart thermostats. Learn where to look, what you agree to in demand response programs, and which…GuideSmart thermostat for a heat pump: what to checkHeat pumps need a thermostat that handles reversing valves and backup heat. Check your wires, the aux heat controls and compatibility before you…GuideSmart control for a ductless mini-splitA mini-split does not use a 24 V wall thermostat. Compare the maker’s Wi-Fi module, a universal IR controller and wired options, and learn where…GuideThermostat wire colors explainedWire colors at the wall plate are a habit, not a rule. Learn what R, Rc, Rh, C, W, Y, G and O/B do, how to read your own wiring safely and when to…GuideSmart thermostat for electric baseboard heatElectric baseboard heaters run on 120 or 240 volts, so a standard 24 V smart thermostat will not work. Here is how to confirm your system, read…GuideAre smart vents worth it?Smart vents promise room-by-room comfort, but closing too many registers can strain your HVAC. Learn the risks, the limits to respect and what to…GuideOne room too hot or cold? Using remote room sensorsRemote room sensors let your thermostat measure the room you actually use, but they cannot fix airflow. Learn how they work, when they help and…GuideSmart thermostat for landlords: limits and tenant controlLandlords can limit a smart thermostat’s range and keep account control, but tenants have privacy and heat rights. See which settings to use, what…GuideWhich smart thermostat fits your HVAC systemMatch a smart thermostat to your equipment before you buy: single-stage, two-stage, heat pump, dual-fuel, baseboard or millivolt. Check wires,…GuideWhich smart thermostat works with Alexa, Google Home and Apple Home?Check three things in this order: your HVAC wiring, whether the thermostat speaks Matter or supports your ecosystem, and which features need an…